Up-regulation of miR-548 m Leading to Neuroinflammation to Promote the Progression of Alzheimer's Disease.

Neuroinflammation mediated by microglia is recognized as a critical contributor to Alzheimer's disease (AD) pathogenesis, and P2RY12 maintains microglial homeostasis. MicroRNAs regulate gene expression post-transcriptionally and have been implicated in modulating microglial activation states during AD by affecting inflammatory pathways. This study aimed to investigate the role of miR-548 m in regulating microglial polarization and neuroinflammation in Alzheimer's disease. Male APP/PS1 transgenic and wild-type mice were utilized as animal models alongside cultured microglial cells for in vitro studies. Behavioral assessments, including contextual fear Morris water maze (MWM) and fear conditioning (FC), evaluated cognitive function. Molecular analyses comprised RT-qPCR western blot, and ELISA, as well as dual-luciferase reporter assays to validate miR-548 m and P2RY12 interactions. In vivo modulation of miR-548 m expression was achieved via stereotaxic intracerebral injections of agomir or antagomir oligonucleotides targeting the dentate gyrus. MiR-548 m was significantly upregulated in AD. Overexpression of miR-548 m promoted microglial M1 polarization characterized by increased pro-inflammatory cytokines (TNF-α, IL-6, iNOS, IL-1β) and reduction in M2 anti-inflammatory markers (Arg1, CD206, IL-4, TGF-β). Inhibition of miR-548 m improved spatial learning and memory performance while attenuating microglial activation in vivo. Luciferase reporter assays confirmed that P2RY12 is a direct downstream target suppressed by miR-548 m. And overexpression of miR‑548 m reversed the inflammatory effects induced by P2RY12 overexpression. These findings demonstrate that elevated miR‑548 m exacerbates neuroinflammation through negative regulation of P2RY12 expression, leading to enhanced microglial M1 polarization during AD progression. Targeting the miR‑548 m/P2RY12 axis may provide a novel therapeutic for mitigating AD.